Many individuals in health care facilities are able to achieve sufficient caloric intake through eating prepared meals. However, a sizable number of such patients are unable to ingest enough food to meet their body's needs. Examples of these individuals would include burn patients, whose daily caloric needs are often in excess of 5,000 calories, and critically ill, weak, or comatose patients who may be unable to chew their food. For these patients, caloric supplementation through parenteral, also known as intravenous, feeding is not a viable alternative.
In response to this problem, liquid foods have been developed for enteral feeding. Enteral feeding is providing nourishment through the oral tract by defined nutritional diets. Typically, enteral feeding utilizes a nasogastric tube to transport the liquid nutritional products from the container through the patient's nasal cavity and thence into the stomach. Early enteral nutritional product containers were empty, sterilized pouches which were filled with sterilized, canned product at the point of use. The filled pouch was spiked by a cannula. However, there are shortcomings associated with that type of packaging including potential product contamination and extensive set-up-time. In response to that problem, a multi-layer plastic bottle was developed having a central layer which provided an oxygen barrier, therefore permitting the bottle to be pre-filled with food product which provided greater shelf-life and less spoilage. This type of plastic bottle utilizes a membrane which must be pierced so as to permit the commencement of the feeding process.
However, a problem arises once cannulation has occurred since the nutritional product container periodically requires the introduction of a small amount of atmospheric air to preclude the establishment of a vacuum in the system, which would terminate the feeding process. This problem has traditionally been overcome in the pre-filled industry by the providing of a valve means to introduce atmospheric air into the enteral nutritional product container. Normally associated with such valve means is a microbial filter.
Ported closures are well known, an example of which is Steidley, U.S. Pat. No. 4,022,258 which discloses a closure for surgical irrigation fluid containers as opposed to one for enteral nutritional product containers. Steidley discloses a large spike member which can pierce a plastic cap with the spike member including a conventional filter positioned adjacent the external surface of the cap. However, Steidley does not address the unique problems associated with the physical composition of enteral nutritional products. Enteral nutritional products are dissimilar from fluids introduced by intravenous feeding primarily due to the presence of minerals and other solids which tend to form a sediment which settles to the bottom of the inverted container during feeding. Additionally, enteral nutritional products are extremely viscous.
Conventional valves associated with enteral nutritional product containers include a ball and an externally positioned filter, both of which are added to the closure structure after the molding process of the closure is completed. Although there has been a long felt need to decrease the manufacturing cost and simplify the manufacturing process associated with the valves by eliminating the ball and redesigning the filter, the fact that the exterior microbial filter currently used prevents contamination of the enteral nutritional product has discouraged experimentation.
It is thus apparent that the need exists for an improved closure for pre-filled enteral nutritional product containers which provides the less costly and more efficient production of such closures, while at the same time ensuring proper microbial filtration.